Wireless networks have evolved over the past decade to provide extensive mobile data and mobile Internet services. Subscribers routinely use their mobile devices to access streaming audio and video, read and send electronic mail, and browse the Internet. To support the increasing use of data and multimedia services, service providers must continually evolve their networks. As mobile data continues to expand, many service providers are moving toward next generation networks, such as Long Term Evolution (LTE) networks. LTE is a 3GPP mobile specification that is designed to provide multi-megabit data rates, efficient radio networks, reduced latency, and improved mobility.
Traditionally, mobile networks have primarily followed two standards-based technologies—GERAN/UMTS and CDMA. GERAN/UMTS-based networks provide a natural evolution to LTE. Many CDMA-based network operators have also decided to evolve toward the LTE specification. Those CDMA operators have evolved their networks to support “evolved High Rate Packet Data” (eHRPD) as a step on the migration path toward LTE. eHRPD allows mobile operators to upgrade existing HRPD packet core networks and integrating them with elements of the Evolved Packet Core (EPC) architecture. eHRPD allows for seamless service mobility and handoffs between the eHRPD and LTE networks.
CDMA operators are undergoing a phased migration in which existing HRPD networks evolve to eHRPD on the way to becoming LTE networks. To introduce eHRPD, a HRPD Serving Gateway (HSGW) is added to the CDMA network. The HSGW also allows the inter-working between eHRPD and EPC. The HSGW supports the connection to S-GW and PDN-GW, ensuring the mobility management between eHRPD and LTE networks so that subscribers experience seamless handover without dropping sessions and with reduced latency.